The publisher didn't see a need, and if you don't lean on Tolkien he was far to easily side tracked to finish things (very much like Leonardo Da Vinci).

And it make a lot more commercial sense to make The Hobbit in the style of LoTR, because the many people who enjoyed the movies but not the books would want to know why Middle Earth had been turned into a twee childish fairytale.

For a professional writer, telling one book in the style of another is a standard exercise. You could do The Hobbit in the style of Dracula, or in the style of Lady Chatterly's Lover, or in the style of a Hayes manual, or in the style of Finnigan's Wake or 20000 leagues under the sea, or [squelch]*

*Fardragon stamped on by a giant foot in the style of Monty Python.A Far Dragon is the best kind...